This invention relates to an automobile constant speed running device which controls a member which influences the fuel/air/mixture gas as, for example, the throttle valve or the fuel injection pump to control the speed of the automobile at a desired set speed.
Various kinds of constant speed running devices (popularly known as "cruise control") are already suggested to improve the comfort of driving cars. For example, an automobile speed adjusting device is mentioned in the gazette of Japanese Patent Publication No. 13731/1982, and has an electric adjustor generating a control signal varying depending on an adjustment difference and an adjusting device to which the control signal is added. The adjusting device has an adjusting member operating a member influencing the fuel/air/mixture gas so that each position of the above-mentioned adjusting member may be detected with a resistance oscillator having a movable part and fixed part and may be transmitted to the adjusting device. The fixed part of the resistance oscillator is fitted so as to resiliently move by a predetermined amount in the moving direction of the movable part and a stopper limiting the displacement of the above-mentioned fixed part is provided on each side of the fixed part so that, in case the movable part moves, the fixed part may be moved together with the above-mentioned movable part in a limited range. Further, a different constant speed running device is mentioned in the gazette of Japanese Patent Publication No. 7294/1982 and is formed of a comparator generating a speed difference signal when a speed difference is generated between a car speed signal corresponding to a car speed and a set car speed signal corresponding to a desired set speed. An actuator adjusts the opening of the throttle valve to increase or decrease the car speed in the direction of eliminating the speed difference signal. The above-mentioned speed difference signal may be fed back to the above-mentioned comparator input through a resistance-capacitance combined delay circuit.
Thus, in the automobile constant speed running device of the convention technique, the member influencing the fuel/air/mixture gas is controlled with a complicated electronic controlling system operated by using an electric signal. Therefore, the formation of the device itself is complicated, the assembling steps for the automobile are many and the producing and assembling costs are high.